I/O configuration data sets

Use the I/O configuration data sets (IOCDSs) to store different I/O configuration definitions for your CPC.

The CPC has four IOCDS slots. The IOCDS slots are: A0, A1, A2, and A3. The IOCDS slots exist on the Support Element (SE) hard disk.

The configuration data in the IOCDS is accessed and transformed to a data format that the Licensed Machine Code (LMC) in the I/O subsystem uses when you perform a power-on reset by selecting Power-on Reset from the Support Element console or Hardware Management Console.

The I/O subsystem then controls I/O requests and uses the configuration data from the IOCDS that you specify for the power-on reset.

IOCP can read from any IOCDS produced by the version of IOCP covered in this document. However, IOCP can write only to an IOCDS that is not write-protected.

You can write-protect each IOCDS individually and remove write-protection when you want to alter an IOCDS by using Input/Output Configuration window of the Support Element. Write-protection prevents you from accidentally using IOCP to write over and destroy the configuration data in an IOCDS. Before writing an IOCDS, you must remove the write-protection from that IOCDS.

When defining a new configuration, you can perform the following actions:

Use the configuration in an existing IOCDS as your operating configuration
Run IOCP to generate and write a new I/O configuration to another IOCDS
Write-protect the new IOCDS
Perform a power-on reset (POR) and use the new configuration to test the system.